User blog comment:TrinityFlare/Question About Steelix?/@comment-30134594-20170404095902

While yes, Ground type is super-effective to fire, it doesn't have any resistance to fire type moves, meaning it would take 1x damage when being damaged by a fire-type move. However, if the Pokemon is dual-typed like Steelix with Steel/Ground, It would be 2x damage taken by Fire because Steel is overall weak to Fire and the Ground typing doesn't help in anyway to make the Fire damage 1x unless the pokemon is Steel/Rock, or is Aggron. This pretty much sums it up.